The present claimed invention relates to a stress component measurement method especially preferably used for measuring a stress component of a measurement specimen whose shape and composition are standardized to a certain degree such as a mass-produced semiconductor substrate.
A stress is a tensor and if a measurement surface is virtually defined, a shear stress component or a normal stress component (collectively called as a stress component) in the measurement surface are determined. As a method for measuring the stress, there are the XRD (X-ray diffraction) and the CBED (convergent beam electron diffraction) as shown in the patent document 1 and the patent document 2. In accordance with the XRD, the stress component of a specimen can be measured without destroying the specimen, however, it takes several minutes to measure one point. In addition, in accordance with the CBED, the stress component of a specimen can be measured accurately by making use of extremely high spatial resolution of less than 100 nm. However, since the specimen has to be destroyed in order to measure the stress component of the specimen, another specimen for measurement has to be prepared separately. As a result, there is a problem that the measuring object is not identical to the separately prepared specimen. In addition, the stress component is measured by the Raman spectroscopy as being a nondestructive testing as shown in the patent document 3. It is possible for the Raman spectroscopy to measure a stress component at one point of, for example, single crystal silicon in a short period of time of several seconds, however, it is difficult to measure all of the stress component. The backscattering layout as being the easiest optical layout of the Raman spectroscopy can measure only a stress of one component.
As mentioned, in case of measuring a stress component, there is some problem in the time required for measurement, non-destructive measurement or a measurable direction of a stress even if either one of the conventional method is utilized.
In addition, a stress is loaded intentionally or in spite of intentions on a micro-structure of a semiconductor device represented by the STI (the shallow trench isolation) by embedding a film of SiO2 or the like, however, it has been known that an electrical property of the semiconductor device changes significantly due to its stress state. Then it becomes necessary to evaluate and administrate the stress value accurately due to recent state that a pattern size of the semiconductor device is miniaturized.
Generally it has been known that the XRD is the most accurate and effective method for measuring the stress/strain of silicon. However, an area that can be evaluated by the XRD is limited due to its measurement principle and the area that can be measured by a commercially available device is several dozen μm at the minimum. On the contrary, since a size of the micro-structure of the semiconductor device such as the STI becomes smaller than sub-μm due to miniaturized pattern size, it is difficult to evaluate the stress by using the XRD.
In addition, the CBED is effective for measuring a strain of sub-μm order or nm order, however, in accordance with the CBED, another specimen for measurement has to be prepared separately because a specimen has to be destroyed in order to measure the strain of the specimen. Furthermore, the CBED is suitable for measurement of extremely subtle area of nm order, however, it takes substantial time to measure a relatively wide area of μm order.
As a result, both methods of the XRD and the CBED are inappropriate as a method for administration in a manufacturing process of the semiconductor devices.
Patent document 1 Japan patent laid-open number Hei1-219529
Patent document 2 Japan patent laid-open number 2000-009664
Patent document 3 Japan patent laid-open number 2006-73866